Diagnosis criteria, such as DMSIV-TR, ICD-10, and PANSS, are currently used as indications in diagnosing psychiatric/neurological disorders, such as schizophrenia, autism, and Alzheimer's disease. However, diagnoses using these criteria are performed by, for example, a medical examination by interview with patients and thus have had the problem of producing variations depending on the evaluator. Thus, there has been a need for a biomarker as an objective biological indication.
Attempts have also been previously made to search for biomarkers for diagnosing psychiatric/neurological disorders. For example, Patent Literature 1 discloses a schizophrenia marker. Patent Literature 2 discloses a biomarker for diagnosing and monitoring mental disorder. However, these markers are not put to practical use in view of accuracy, easiness to practice, cost, and the like.